Multimode multicarrier modem system and method of communication over the same

ABSTRACT

An alternative approach to coping with the ever increasing demand for faster communications hardware is to design modems that are capable of operating its speeds at a higher data rate than a speed required for a single port of the standard communication rate for that modem. Basically, by utilizing a resource manager, that directs the data in and out of the various portions of the modem in an orderly manner, keeping track of which of the ports is being operated at any given point in time, a standard single port modem can be reconfigured, for example, at an over clocked rate, to manipulate the data input and output of a modem.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to communications technologies. In particular,this invention relates to a multimode multicarrier modem.

2. Description of Related Art

The role out of broadband services over telephone lines using DigitalSubscriber Lines (DSL) technology is occurring around the globe. Inorder to achieve reliable communications over DSL links, a techniqueknown as Discrete Multitone (DMT) modulation is used. Discrete MultitoneModulation has been standardized for DSL transmission by the ANSIstandards body for full-rate ADSL (T1E1.4/97-007R6 Interface betweennetwork and customer installation Asymmetric Digital Subscriber Line(ADSL) metallic interface, Sep. 26, 1997, i.e., T1.413 Issue 2,incorporated herein by reference in its entirety, and by theInternational Telecommunication Union (ITU) in the G.992.1 (full-rateADSL) and G.992.2 (G.lite) standards, both incorporated herein byreference in their entirety. These standards specify that hundreds of4.3125 kHz sub-channels are assigned for DSL transmissions between atelephone company Central Office (CO) and a Remote Terminal (RT), suchas a home or business. Data is transmitted between the CO and RT in boththe downstream direction, i.e., from the CO to the RT, and in theupstream direction, i.e., from the RT to the CO. The aggregatebandwidth, i.e., the bandwidth that is used by both the upstream and thedownstream communications, of a full-rate ADSL system is over 1 MHz andthat of G.lite is over 500 kHz. The systems typically transmit 1.5 Mbps(G.lite) or 6 Mbps (full-rate ADSL) data rates downstream.

SUMMARY OF THE INVENTION

The demand for even faster data access speeds is being driven by thedesire of consumers to enhance access to the Internet and servicesavailable over the Internet, such as high-bandwidth multimediapresentations, streaming video, audio, streaming audio, and the like.This increased demand in turn creates a demand for systems andtechnologies that are capable of operating at these increasedbandwidths. Communication systems that enable high speed data access arebeing developed for both wireline and wireless systems. Typically, thesesystems combine a highly sophisticated signal processing technique thatenables multiple bits per second per hertz of bandwidth in conjunctionwith an operational range over wider and wider bandwidths.

For example, to cope with these demands, proposed solutions include whatis known as VDSL (very high speed DSL) utilizing approximately 10 MHz ofbandwidth. Utilizing more bandwidth allows an even greater potential ofhigher data rate services using these technologies. For example,services based upon VDSL are targeting data rates in excess of 20 Mbpsdownstream, and in some cases, in excess of 50 Mbps.

Another example of broadband technology is known as home networking. Forhome networking, technology solutions propose the use of betweenapproximately 10 and 20 MHz of bandwidth to supply approximately 10 Mbpsof throughput between multiple points within the home. Some of the mediabeing considered for home networking are the telephone wires inside thehome, electrical wires inside the home, wireless transmissions, or thelike.

In general, and with reference to FIG. 1, the telephone networkarchitecture is a star network. A central office exists in eachneighborhood throughout the world that connects all the customers withina geographic location together. Many thousands or tens of thousands oftelephone lines may aggregate at the central office. Equipment in thecentral office that is used for DSL service should thus be capable ofserving multiple lines as cost-effectively and space-effectively aspossible.

Multi-port solutions are based upon technology that uses a siliconarchitecture that can support multiple DSL lines in a single chip. Wherea single port solution can support one DSL line, a multi-port solutionis capable of supporting many DSL lines. By using advances in thesemiconductor process technology, a single piece of silicon can supportmultiple lines whereas historically the same silicon can only supportone line. Multi-port solutions are an example of an important part ofthe evolution of DSL solutions and leverage the improvements in siliconprocesses to create a solution that translates into, for example, costsavings and space savings for DSL service providers.

Accordingly, and in accordance with an exemplary embodiment of theinvention, the first aspect of this invention is to provide anarchitecture that enables systems to support both multi-portstandards-based DSL and broadband technologies.

Aspects of the present invention also relate to providing anarchitecture that scales as silicon geometry's change so that anarchitecture that supports x ports today can support y, where y isgreater than x, ports in the future.

Aspects of the present invention also relate to providing anarchitecture that scales to support multiple modes of operation so thatthe systems and methods can evolve from supporting a predeterminednumber of ports of one solution or a predetermined number of ports foranother solution. For example, an exemplary multiple mode embodiment mayinclude 8 ports of DSL or 1 port of VDSL, or 2x ports of one solution or2y ports of another solution, such as 16 ports of DSL or 2 ports ofVDSL.

Aspects of the present invention also relate to providing a modemarchitecture that is capable of supporting both access solutions, suchas DSL, cable, powerline or wireless access, or the like, and homenetworking solutions, such as powerline, telephone line, wirelessnetworking, or the like.

Aspects of the present invention also relate to providing a method foroperating a modem in one of number of modes of operation.

These and other features and advantages of this invention are describedin, or are apparent from, the following detailed description ofembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention will be described in detail, withreference to the following figures wherein:

FIG. 1 is an exemplary embodiment of a star network;

FIG. 2 is a functional block diagram illustrating an exemplary multimodemulticarrier modem according to this invention;

FIG. 3 is a functional blocked diagram illustrating a second exemplaryembodiment of a multimode multicarrier modem according to thisinvention;

FIG. 4 is a functional blocked diagram illustrating a third exemplarymultimode multicarrier modem according to this invention;

FIG. 5 is a functional block diagram illustrating a fourth exemplarymultimode multicarrier modem according to this invention;

FIG. 6 is a functional blocked diagram illustrating an exemplaryresource manager according to this invention;

FIG. 7 is a functional blocked diagram illustrating a second exemplaryresource manager according to this invention;

FIG. 8 illustrates the exemplary operation of a resource manageraccording to this invention;

FIG. 9 illustrates a second exemplary method of operation of theresource manager according to this invention; and

FIG. 10 illustrates the exemplary operation of an 8 port ADSL modemaccording to this invention; and

FIG. 11 illustrates the exemplary operation of a VDSL modem according tothis invention.

DETAILED DESCRIPTION OF THE INVENTION

For ease of illustration, the functions of an exemplary DSL modem havebeen partitioned into sections, where each section is dedicated toperform at a certain function. However, it is to be appreciated, thatthis division is simply for ease of illustration, and that thefunctional components of the modem can be regrouped or re-associated inany way as deemed appropriate. For the exemplary embodiments of thisinvention, the DSL modem will be broken into four functional components.First, the ATM over ADSL interface block implements the ATM transmissionconversions layer as defined in the ITU 1.432 standard. This interfaceblock provides the connectivity from the ATM-Forum UTOPIA-Level IIinterfaces to a full duplex synchronous serial port that is typical onADSL devices. Secondly, the framer block, which includes, for example, aframer, a coder, and interleaver blocks, implements the bit orientedfunctions of T1.143 and G.lite standards, such as, framing, a CyclicRedundancy Check (CRC), scrambling, Reed-Solomon coding, andinterleaving. Third, the transformation block implements the multitoneQAM and trellis constellation encoding and/or decoding, Fouriertransforms, and frequency-domain equalization algorithms that enabletransmission and reception according to the requirements of the FullRate and G.lite standards. Fourth, the equalization block implements thedigital filtering portions of the front-end processing required in anADSL modem. The filters perform plain old telephone system (POTS)protection, transmit mask application, interpolation, decimation, echocancellation and time domain equalization (TDQ). Furthermore, each ofthese blocks is capable of supporting both transmit and receivefunctions simultaneously. The transmit functions implemented in theseblocks are detailed in the G.992.1 and G.992.2 standards, incorporatedherein by reference in their entirety. The receive functions detailedabove are just a typical example of an ADSL receiver. It is toappreciate that other receiver structures are possible and that thereceiver structure is not limited to that described herein.

Within each functional unit described above, there exist core engines,or functional blocks, that operate on data being processed in the modem.For example, in a single port solution, there will exist one such set ofengines in each functional block. As solutions have migrated tomulti-port applications, a typical solution is to populate the DSL modemarchitecture with multiple engines with each engine dedicated to theequivalent of one DSL line's implementation.

FIG. 2 illustrates an exemplary multi-port solution that uses thepartition nomenclature discussed above for a 4-port embodiment. Inparticular, for each port, each one of the blocks, i.e., the interfaceblock, the framer block, the transformation block, and the equalizerblock, is duplicated. However, with the exemplary embodiment illustratedin FIG. 2, the size of the resulting silicon solution, which is directlyrelated to the number of gates required to implement the modem, becomesdisadvantageously large. Since the same blocks are replicated multipletimes, the size of the silicon grows as more ports are added to themodem.

According to an exemplary embodiment of this invention, modems aredesigned that are capable of operating at speeds that are higher thanthe speed required to implement a single port of DSL. Thus, one enginecan be used to support the throughput of multiple engines. Therefore, byre-using the same engine multiple times, the number of gates requireddoes not increase relative to the number of ports. Typically, as thegeometry of the silicon implementation, measured in microns, decreases,the speed at which a chip can operate increases. For a factor of twoimprovement in silicon geometry, e.g., from 0.35 microns to 0.25microns, a speed increase of approximately of 30% can be achieved. Theresult is that as silicon manufacturing processes improve, andconsequently solutions proceed deeper into the sub-micron realm, thesame DSL engine that in a previous geometry can only operate one port,in the new geometry according to the systems and methods of thisinvention allow more than one port can be supported. To provide thistype of functionality, a resource manager that directs the data in andout of one or more engines and maintains information pertaining to whichof the ports is being operated at any particular time is used.

For example, FIG. 3 illustrates an exemplary embodiment of a multimodemulticarrier modem that is capable of supporting multiple portssimultaneously. In particular, as previously discussed, the multimodemulticarrier modem 100 comprises an interface block 200, a framer block300, a transformation block 400, an equalizer block 500 and a resourcemanager 600, interconnected by links 5. In this exemplary embodiment,the framer 300 comprises a framer CRC scrambler 310, an inverse-framerCRC descrambler 320, a Reed Solomon Coder 330, a Reed-Solomon Decoder340, an interleaver 350 and a deinterleaver 360. The transformationblock 400 comprises a QAM encoder trellis 410, a QAM decoder trellis420, an equalizer 430, a DMT modulator (IFFT) 440 and a DMT demodulator(FFT/FDQ) 450. The equalizer block 500 comprises an interpolator andecho cancellor 510 and an echo cancellation and time domain equalizer(TDQ) 520.

The links 5 can be a wired or a wireless link or any other known orlater developed element(s) is capable of supplying and communicatingelectronic data to and from the connected elements.

Thus, for example, in the exemplary embodiment illustrated in FIG. 3, amulticarrier modem is capable of, for example, allocating 32 Mbps to beused to support 4 ports of 8 Mpbs ADSL or 1 port of 32 Mbps VDSL. Thisis accomplished by changing the operation of the resource manager 600.For example, the modifications to the resource manager 600 can be asoftware command that regulates the operation of the various engines anddirects and maintains the input and data output from the resourcemanager 600. With this exemplary embodiment, the number of transistorsrequired to implement a multi-port solution and the ability, throughsoftware commands, to configure the silicon to operate as either amultiport ADSL or, for example, a VDSL solution, is provided.Furthermore, it is also possible to configure the silicon to operate ina combination of ADSL and VDSL ports. In the example illustrated in FIG.3, where a 32 Mbps engine is used in the example, the engine can bereconfigured to support one 8 Mbps ADSL port and two 12 Mbps VDSL ports.

In operation, the resource manager 600 comprises a memory portion and aresource multiplexing system (not shown) that is capable of managing theaddressing and control functionality into and out of one or morefunctional blocks. Thus, depending on the service requirements, e.g.,ADSL, VDSL, Home Networking, or any combination thereof, the resourcemanager 600, allocates for each service requirement and for eachfunctional block determines the required frame boundaries based on theservice requirement. Additionally, the resource manager 600 divides thememory portion into, for example, a number of buffers, based on theframe boundaries and configures the addressing of data read into anddata written out of the buffers to the respective functional blocks.

FIG. 4 illustrates an exemplary embodiment of a multimode multicarriermodem 1000 according to a second embodiment of this invention. Inparticular, and while similar components are referred to with similarreference numbers, the functions of the resource managers are splitbetween one or more of the various functional blocks. For example, inthis illustrative embodiment, the resource manager 610 is placed betweenthe interface block 200 and the framer block 300. Furthermore, theresource manager 620 is placed between the framer block 300 and thetransformation block 400, and the resource manager 630 is placed betweenthe transformation block 400 and the equalizer block 500. Therefore, forthis particular embodiment, the duties of the various resource managersare restricted to directing the data in and data out between twoadjacent functional blocks. However, it is to be appreciated, that whilethe resource manager can be configured to govern all functional blocks,such as illustrated in FIG. 3, or have multiple resource managers withmore specific functionality, the resource manager or resource managers,can be configured in any manner, and duplicated as many times asnecessary, without affecting the overall function of the systems andmethods of this invention.

FIG. 5 illustrates that exemplary multimode multicarrier modem 1100 thatcan provide, for example, concurrent DSL access and home networkingsolutions either simultaneously, or serially. In particular, amulticarrier, e.g., DMT, based home networking solution can bepartitioned into similar functional portions comparable to thosediscussed above. This partitioning results in a silicon architecturethat consists of a very high-speed engine, or one or more engines, thatcan support both ADSL and home networking. In particular, themulticarrier modem 1100 comprises a MAC (media access control)functional block 700, a transformation block 400 and a equalizer block500, with resource managers 640 and 650 interposed therebetween,respectfully. However, as discussed in relation to a previous embodimentof the multimode multicarrier modem, the resource manager 640 and 650can be combined into one resource manager that is capable of controllingthe MAC block 700, the transformation block 400 and the equalizationblock 500.

In operation, the resource managers 640 and 650 comprise a memoryportion and a resource multiplexing system (not shown) that is capableof managing the addressing and control functionality into and out of onethe MAC 700 and transformation functional blocks 400 and thetransformation and equalization block 500, respectively. Thus, theresource manager 640, determines the required frame boundaries based onthe service requirement. Additionally, the resource manager 640 dividesa memory portion (not shown), such as a buffer, into, for example, anumber of buffers, based on the frame boundaries and configures theaddressing of data read into and data written out of the buffers to therespective functional blocks.

FIG. 6 illustrates an exemplary embodiment of the various functionalcomponents of a resource manager that is used for a plurality ofcomputational engines. In particular, the resource manager 600 comprisesa memory and resource multiplexing control portion that provides theaddress and control functionality for the various engines in themultimode multicarrier modem. Additionally, two buffers, an encoderoutput buffer 660 and an inplace buffer 670 are used to temporarilystore information between the associated functional blocks. As discussedabove, based on the number of ports, the resource manager configures thememory portion and the multiplexing control to control the transfer ofdata into and out of the various functional blocks using, for example, atime slot type organizational structure.

FIG. 7 illustrates an exemplary configuration for a plurality ofresource managers where each resource manager is assigned an engine. Inparticular, a Reed-Solomon resource manager 710 manages the addressingand control of the Reed-Solomon encode engine with the aid of theencoder output buffer 660. Similarly, the constellation encode resourcemanager 720 manages the addressing and control of the constellationencode engine with the aid of the encoder output buffer 660 and the FFTinplace buffer 670. Additionally, the FFT resource manager 730 managesthe addressing and control of the FFT MACC encode engine with the aid ofthe FFT inplace buffer 670.

FIG. 8 illustrates an exemplary method of operation of a resourcemanager. In particular, control begins in step S100 and continues tostep S110. In step S110, the service requirements are established. Forexample, the modem can be configured to operate in a single, such ashigh speed mode, a mulit-mode configuration, or any combination thereof.Next, in step S120, for each service type, the operation of resourcemanager is determined. Then, in step S130, for each resource manager,the frame boundaries are determined in step S140. Control then continuesto step S150.

In step S150, the memory, or buffers, are divided based on the frameboundaries. Next, in step S160, the addressing of the resourcemanager(s) are configured to correctly route data between the variousfunctional blocks. Control then continues to step S170 where the controlsequence ends.

FIG. 9 illustrates a second exemplary method of the operation of aresource manager. In particular, control begins in step S200 andcontinues to step S120. In step S210, the service requirements areestablished. For example, the modem can be configured to operate in asingle, such as high speed mode, a mulit-mode configuration, or anycombination thereof. Next, in step S220, a determination is made wetherthe modem is to be configured for ADSL multiport mode. If the modem isto be configured for ADSL multiport mode, control continues to stepS230. Otherwise control jumps to step S260.

In step S230, the frame boundaries are established. Next, in step S240,a buffer is configured as an inplace buffer containing a predeterminednumber of points. Then, in step S250, the addressing for the buffer isconfigured. Control then continues to step S340.

Next, in step S260, a determination is made wether the modem is to beconfigured for LAN operation. If the modem is to be configured for LANoperation, control continues to step S270. Otherwise control jumps tostep S300.

In step S270, the frame boundaries are established. Next, in step S280,a buffer is configured as an inplace buffer containing a predeterminednumber of points. Then, in step S290, the addressing for the buffer isconfigured. Control then continues to step S340.

Next, in step S300, a determination is made wether the modem is to beconfigured for VDSL operation. If the modem is to be configured for VDSLoperation, control continues to step S310. Otherwise control jumps tostep S340.

In step S310, the frame boundaries are established. Next, in step S320,a buffer is configured as an inplace buffer containing a predeterminednumber of points. Then, in step S330, the addressing for the buffer isconfigured. Control then continues to step S340 where the controlsequence ends.

However, while the exemplary method illustrated in FIG. 9 shows thevarious methods being operated serially, it is to be appreciate that thevarious steps could also be run in parallel. For example, the multiportADSL and VDSL steps could be performed simultaneously, for example bydedicated resource managers.

FIG. 10 illustrates the exemplary addressing for a resource manager fora functional block where the modem is configured for 8 ports of ADSL. Inparticular, for each port, a 512 point FFT inplace buffer isestablished. The resource manager then performs 768 Multiply-accumulatesper pass, addressing local to the port 1 FFT buffer. Similar operationsare also performed for the remaining 7 ports.

For the exemplary 8-port example, and with reference to FIG. 10, thefunctional logic, which is directionally related to the numbers ofgates, are required to support 8 ports of 8 Mbps ADSL is essentiallyequivalent to that required for one port of 64 Mbps VDSL. The number ofFFT “butterfly” operations for one 8 MHz VDSL with a 4096 point FFT isonly slightly larger than the number of butterflies required for 8 portsof ADSL, each utilizing 1 MHz of bandwidth. Thus, the same computationalresources and the even the same memory buffers can be re-used withdifferent addressing and logic control as managed and identified by theresource manager.

FIG. 11 illustrates the exemplary addressing for a resource manager fora functional block where the modem is configured for 1 ports of VDSL. Inparticular, a 4096 point FFT inplace buffer is established. The resourcemanager then performs 6144 Multiply-accumulates per pass, addressingthroughout the 4096 point buffer.

The above example refers to the FFT functional block that is used in theDMT transmitter and receiver. The same concept of scaling theimplementation engine to support multiple applications applies to otherfunctional blocks as well. For example, primary resources required toperform the Galois-Field operations for the two cases above, i.e., 8ports of 8 Mbps ADSL or 1 port of 64 Mbps VDSL, are the same, i.e.,32,000 length-255 Reed-Solomon code words must be computed each second.

The multimode multicarrier engine described in this invention can beused in applications where a multicarrier engine is a fundamentalelement of a set of access solutions or a combination of access andnetworking solutions. The exemplary embodiment provides details of amultimode ADSL or VDSL solution as well as a combination mode ADSL/LANsolution. Multimode operation can also involve a selection between anyof ADSL, VDSL, powerline access, i.e., transmission and reception ofdata over powerlines, wireless access, i.e., transmission and receptionof data over the air, or cable access, i.e., transmission and receptionof data over cable TV lines. As described above for ADSL or VDSL,multimode operation can also involve combinations of access techniquesdriven out of the multimode engine, e.g., 2 ports of ADSL and 1 port ofVDSL. Also, while the exemplary embodiments discussed above illustrate acombination mode operation involving a selection of access andnetworking technologies and a combination ADSL/LAN operation, anycombination of access, such as ADSL, VDSL, powerline, wireless or cable,and networking, such as, telephone line, powerline, wirelesstechnologies, or the like, can also be used with comparable success.

As illustrated in FIG. 3-7, the multimode multicarrier modem and relatedcomponents can be implemented either on a DSL modem, such as a VDSLmodem, or separate programmed general purpose computer having acommunication device. However, the multimode multicarrier modem can alsobe implemented in a special purpose computer, a programmedmicroprocessor or a microcontroller and peripheral integrated circuitelement, an ASIC or other integrated circuit, a digital signalprocessor, a hardwired or electronic logic circuit such as a discreteelement circuit, a programmable logic device, such as a PLD, PLA, FPGA,PAL, or the like, and associated communications equipment. In general,any device capable of implementing a finite state machine that is inturn capable of implementing the flow charts illustrated in FIGS. 8-9can be used to implement the multicarrier modem according to thisinvention.

Furthermore, the disclosed method may be readily implemented in softwareusing object or object-oriented software development environments thatprovide portable source code that can be used on a variety of computers,work stations, or modem hardware and/or software platforms.Alternatively, disclosed modem may be implemented partially or fully inhardware using standard logic circuits or a VLSI design. Other softwareor hardware can be used to implement the systems in accordance with thisinvention depending on the speed and/or efficiency requirements of thissystem, the particular function, and the particular software and/orhardware systems or microprocessor or microcomputer systems beingutilized. The multicarrier modem illustrated herein, however, can bereadily implemented in a hardware and/or software using any known laterdeveloped systems or structures, devices and/or software by those ofordinary skill in the applicable art from the functional descriptionprovided herein and with a general basic knowledge of the computer andtelecommunications arts.

Moreover, the disclosed methods can be readily implemented as softwareexecuted on a programmed general purpose computer, a special purposecomputer, a microprocessor and associated communications equipment, amodem, such as a DSL modem, or the like. In these instances, the methodsand systems of this invention can be implemented as a program embeddedon a modem, such as a DSL modem, or the like. The multicarrier modem canalso be implemented by physically incorporating the system and methodinto a software and/or hardware system, such as a hardware and softwaresystem of a modem, such as an ADSL modem, VDSL modem, network interfacecard, or the like.

It is, therefore, apparent that there has been provided in accordancewith the present invention, systems and methods for a multimodemulticarrier modem configuration. While this invention has beendescribed in conjunction with a number of embodiments, it is evidentthat many alternatives, modifications and variations would be or areapparent to those of ordinary skill in the applicable art. Accordingly,applicants intend to embrace all such alternatives, modifications,equivalents and variations that are within the spirit and the scope ofthis invention.

1. A multicarrier modem comprising one or more resource managers thatallow the modem support a plurality of modes of operation. 2-18.(canceled)